SC908 View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'SC908' PDF : 30 Pages View PDF
SC908
Applications Information (continued)
from 2.77V to 2.98V, ±10%. The low battery fault threshold
is set by the relationship
VDET = 3.9 μA × RRLBAT × 2.42
RRLBAT must satisfy the condition
294kΩ ≤ R ≤ 316kΩ
RLBAT
Connect RLBAT to GND to disable the Low Battery Detector
fault. The Low Battery Detector warning remains active.
Status Outputs
Four charger status outputs/LED drivers are provided.
• CPB (Charger Present)
• CHRGB (Charge Active)
• FLTB (Fault)
• LBATB (Low Battery Warning)
These outputs are active-low, open drain NMOS drivers
capable of sinking up to 2mA each. The state of each, in
various operating conditions, is defined in Tables 2, 3,
and 4.
When the VAD voltage is below its UVLO threshold (no
charging adapter is present), the CPB and CHRGB outputs
are off (high impedance). The FLTB and LBATB outputs
indicate the battery voltage as defined in Table 2.
When V is between its UVLO and OVP thresholds, V
VAD
VAD
is valid to charge, and the CPB output is low indicating
that a charging adapter is present.
The CHRGB output indicates the battery charging status.
The charger-present status output states are described in
Table 3. When pre-charging or when the output current
is greater than ITERM, CHRGB is low. The CHRGB output is
latched off (high) when the output current becomes less
than I during the charge cycle (and the battery voltage
TERM
is above the recharge threshold, VBSEN > VCV - VTReQ). This
latch is reset when the battery enters a recharge cycle
(V < V - VT ), or for any NTC_EN range other than
BSEN
CV
ReQ
OK-to-charge, or if VVAD is above or below the VAD valid-
to-charge range, allowing CHRGB to become active again
when charging resumes.
When a charging adapter is present, the FLTB and LBATB
outputs are redefined to reflect the interaction of the
battery voltage, charging state, and charging faults, as
described in Table 3. The FLTB output is activated when
the device experiences a charger fault condition, or
(together with LBATB output) when the battery voltage is
less than the resistor-programmed low-battery detector
threshold, V . This output can be used to notify the
DET
system controller of a fault condition when connected to
an interrupt input, or it can be used like CPB and CHRGB
to drive an indicator LED.
Table 2 — Status Output State, Charging Adapter Absent
Status Pins Output State
(on = low)
Conditions
Adapter Voltage
Battery Voltage
(mutually exclusive) (mutually exclusive)
Description
and
Comments
off off off off
T
off off off on
T
off off on on
T
on = open drain output driver is active
off = output is not active
T = listed condition is true
F = listed condition is false
- = don’t care
Blank = mutually exclusive with another condition
T
No Charging Adapter, Battery Voltage Good
T
No Charging Adapter, Low Battery Voltage Warning
T No Charging Adapter, Low Battery Shutdown Request
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